Jack Dorsey has stepped down as chief executive of Twitter, the social network he co-founded nearly 16 years ago, turning over the top spot to Parag Agrawal, the company's chief technology officer. 

"I've decided to leave Twitter because I believe the company is ready to move on from its founders," Dorsey, who is also CEO of payments company Square, said in a statement Monday. "My trust in Parag as Twitter's CEO is deep."

Dorsey will remain on Twitter's board through the end of his term in 2022 to help with the transition. CNBC reported the move earlier Monday.

The leadership shift comes amid mounting scrutiny of Dorsey and Twitter from investors seeking better returns and from lawmakers concerned about the company's moderation policies for political speech. Last year, Elliott Management, an activist investment fund, began putting pressure on Dorsey to step aside after the CEO said he wanted to spend up to half a year in Africa. The fund ultimately struck a deal with the company that allowed Dorsey to remain CEO. The deal included an influx of $1 billion in new capital from Silver Lake, a large technology investor.

Twitter has also pushed back against accusations it censors conservative politicians and commentators but also took the rare step earlier this year of permanently banning Donald Trump, who was president at the time, because of concerns his remarks could incite violence after the Jan. 6 Capitol Hill riot. 

Under Dorsey's leadership, Twitter has more aggressively experimented with new features including newsletters, live audio and tipping to rope in more users. He also oversaw the company's first profit, which it recorded in 2018, and set a goal of doubling its annual revenue to at least $7.5 billion in 2023. Twitter, which has 211 million daily users who see ads, wants to reach at least 315 million daily active users in 2023. 

Elliott Management managing partner Jesse Cohn and senior portfolio manager Marc Steinberg expressed support for the leadership changes.

"Twitter is now executing against an ambitious multi-year plan to dramatically increase the company's reach and value, and we look forward to the next chapter of Twitter's story," the pair said in a statement.

In a farewell email to Twitter employees, Dorsey sidestepped the issue of external pressure, saying he was leaving the company because it was ready to move past a "founder-led" structure.

"I want you all to know that this was my decision and I own it," Dorsey wrote in the email, which he also tweeted. "I'm really sad…yet really happy."

Dorsey expressed confidence in Agrawal's ability to run Twitter, saying "he leads with heart and soul, and is someone I learn from daily."

Agrawal joined Twitter in 2011 and has served as the company's CTO since 2017. As CTO, he led the social network's technical strategy and advanced the use of machine learning at Twitter, according to the company. 

Agrawal followed up with his own note to employees, also shared on Twitter. In the note, he said he's focused on the company's opportunities ahead. 

"We recently updated our strategy to hit ambitious goals, and I believe that strategy to be bold and right," he wrote. "But our critical challenge is how we work to execute against it and deliver results -- that's how we'll make Twitter the best it can be for our customers, shareholders and for each of you."

Agrawal, who has more than 109,600 followers on Twitter, doesn't share his thoughts often on the social network. He's tweeted or retweeted only 24 times this year, according to his timeline. Dorsey has 5.9 million followers on Twitter. 

The company's stock spiked following news reports on Monday morning and settled about 3% higher. Trading was then halted. 

Dorsey had been CEO of the social network since 2015, when he took over following the resignation of Dick Costolo. Dorsey also briefly served as Twitter's first CEO starting in 2007 but was fired 16 months later. 

Twitter went through a rough patch when Dorsey first returned. In 2016, the company cut 9% of its workforce, and reports surfaced that multiple companies, including Disney and Salesforce, were interested in buying Twitter. No deal materialized. The company also killed off short-form video app Vine before TikTok rose in popularity. 

Dorsey also shepherded the company through a period of intense scrutiny of social media platforms. Along with Mark Zuckerberg, the CEO of Facebook's parent company, Dorsey became a frequent visitor to Congress, testifying at multiple hearing on social media. (Watch a highlight reel of Dorsey's and Zuckerberg's November 2021 appearance before the Senate here.)

Throughout his tenure at Twitter, Dorsey has cultivated the image of New Age tech guru. He eats one meal a day and takes ice baths. according to The New York Times, which called him "Gwyneth Paltrow for Silicon Valley." Dorsey also goes on meditation retreats, which have occasionally gotten him into trouble. In 2018, the executive faced vocal criticism for traveling to Myanmar on a meditation retreat amid international accusations the country's military had committed widespread human rights abuses against the country's Rohingya people, a Muslim minority. 

Dorsey's ownership stake in Twitter has made him a billionaire. The Bloomberg Billionaires Index ranks Dorsey as the world's 174th richest person, with more than $12 billion in assets.  

According to a document filed with the SEC, Agrawal will receive a salary of $1 million. By comparison, Dorsey famously took a 2018 salary of $1.40, one cent for each of the number of characters tweets were initially limited to. (Agrawal is also eligible for a bonus and stock grants.) 

Dorsey remains CEO of Square, a digital payments company he co-founded in 2009. In July, Square said it would launch a new business focused on bitcoin  to help developers design decentralized financial products. Dorsey is an enthusiastic supporter of bitcoin and helped form an endowment to make it the "internet's currency."